1. Field of the Invention
Aspects of the present invention relate to an insulating case for a secondary battery and a secondary battery having the same.
2. Description of the Related Art
Secondary batteries can be repeatedly charged and discharged, and thus, they are more economical than disposable batteries. Moreover, because secondary batteries can realize a high capacity in a small volume, they are in wide use as power sources for portable electronic devices, such as cellular phones, notebook computers, camcorders, digital cameras, etc.
Secondary batteries include, for example, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium ion secondary batteries, lithium polymer secondary batteries, etc. Lithium ion secondary batteries are widely used, because they can be fabricated at a small size, while having a high capacity, a high operating voltage, and a high energy density per unit weight.
Lithium ion secondary batteries may be classified as can-type and pouch-type, according to the shape of a case accommodating an electrode assembly. An electrode assembly generally includes a positive electrode plate, a negative electrode plate, and a separator. Can-type batteries may be classified as prismatic or cylindrical, according to the shape thereof.
The case of a prismatic lithium ion secondary battery is formed of a metal such as aluminum, and the corners thereof may be rounded. A prismatic lithium ion secondary battery is fabricated by inserting an electrode assembly and an electrolyte into a can, through an opening thereof, and then sealing the opening with a cap assembly. A prismatic lithium ion secondary battery includes an insulating case located at the top of the electrode assembly, so as to prevent the electrode assembly from moving, and to prevent a short circuit between the electrode assembly and the cap assembly.
If the internal temperature of the secondary battery reaches, for example, 110° C. to 130° C., the upper end of the separator contracts. As a result, the positive electrode plate and the negative electrode plate may be short-circuited, which may result in a fire or an explosion.